Electromagnetic chuck



March 12, 1929. J. ems

ELECTROMAGNETIC CHUCK Filed July 14, 1927 Patented Mar. l2, 1929.

UNITED STATES 1,704,783 PATENT OFFICE;

JULIUS DING, OI msmucn, GERMANY, ASBIGNCB TO THE FIB-K Cm-Wm G. I. B. B. EISENACE SPEZIAL-FABBIK m ELEKTBOIAGNET-APPABATE, OI'

eon, e.

ELECTROMAGNETIC CHUCK.

Application fled July 14, 1927, Serial No. 205,686, and in Germany September 94, "II.

This invention relates to electro-magnetic chucks of the type in which the work-pieces are placed in continuous succession onto a rotating chuck and after being worked upon are again taken away in succession from said chuck. In known devices of this kind the chuck consists of a casing which surrounds the magnet-winding and whose under part is fixed relatively to said windin while the pole-plate or'chuck proper, whic serves for the reception of the work-pieces, is rotated and forms a cover for the casing of the magnet-winding.

This construction is connected with the 16 disadvantage that the strong forces of attraction which are exerted by the magnetcasing upon the rotating pole-plate mustbe fully taken up by the hearing which is provided for the holding plate. There is furthermore a disadvantage connected with the known constructions, which consists therein that it is diflicult to provide a close fit between the rotating holding plate and the fixed magnet-casing. By reason of the continuous alternate expansion and contraction of the several parts of the device which is due to alternate heating and cooling, the liquid which serves for the cooling 0;E the workpiece may easily pass through the gap between the magnet-casing and the rotating holding late and enter the interior of the casing, w ere it may cause damage by shortcircults or grounds. I

My invention avoids the aforementioned disadvantages by doing away with a closed casing for the magnet-windings and by reviding in addition to the rotating hol ing plate which serves for the reception of the work-pieces a further plate on the under side of the magnet-system, said latter plate servin as a yoke or said magnet-system and being arranged so as to be rotated together with the holding or pole plate independently or the magnet-system.

My invention comprises further im rovements regarding the exciter-windings or the magnetstem, said improvements consisting therein t at two ma et-systems of opposite polarit are provided which are placed diametrical y to each other thus leaving a pair of oppositely positioned neutral zones intermediate the magnet-system, whereby the work-pieces will be fully de-magnetlzed within said zones. In this manner the workpieces may be conventiently removed from the holdlng plate after being worked upon. This is a considerable advantage as compared with chucks of known construction, whereby the work-p eces after having passed the working zone w1ll et be rather firmly attached to the holding p ate so that they must be taken away from the latter with some force and subsequently be subjected to a ,special de-magnetlzing process.

In the drawings I have shown in a somewhat diagrammatical way an example of a construction of the electro-magnetic chuck according to my invention, Fig. 1 being a vertical section through the axle of the new chuck and Fig. 2 being a section taken on the righthand side alon the line 0-13 and on the left-hand side 0 Fig. 1 along the line O-A.

In the drawing the reference numeral 1 designates the holding plate or pole-plate serving for the reception of the work-pieces. This holdin plate is provided at its periphery Wlth a ange 2 extending in downward direction and is mounted rotatably around a vertical axis by means of the axle 3. The axle 3 is mounted in ball-bearings 4 and 5 and may be set in rotation by means of the bevel gears 13. Underneath the poleplate 1 there are provided two fixed magnet-systems 7 and 7, a proper air-gap 6 being left between the magnebsystems 7 and '1 and the plate 1. The cores 8 of the magnet-systems are made in the form of hollow cylindrical sectors which are concentrically arranged with respect to the axle 3 off the device. Either group of magnet-cores oomprises three cylindrical sectors, as ma be seen from Fig. 2, the three sectors 0 one group of magnet-cores bein arran ed oppositely to the three sectors 0 the ot er group and all of said sectors extending approximately through an angle of 120 degrees around the periphery of theole-plate 1. Each magnet-core 8 is provid with an exciter-win ing 9 which may be supplied with electric current by means of fixedly connected conductors. O posite to each magnet-core 8 there is provi ed on the pole-plate 1 a ring 10 of magnetizable material which serves for closing the magnetic lines of force enerated by the magnet-systems 7 and 7'. e rings or strips 10 of magnetizable material are ac arated from each other by rings or strip; 1

cores are freely exposed and of non-magnetizable material, for instance brass. On the under side of the device the magpetic lines of force are closed by means f t e plate 12 which serves as a yoke for the magnet-systems. The plate 12 is fixedly mounted on the axle 3 below the magnetsystems 7 and 7, asmall air-gap being provided between said plate 12 and said magnetsystems. The pole-plate 1 may therefore be rotated in unison with the yoke-plate 12 relatively to the magnet-systems 7 and 7. B this arrangement of the plates 1 and 12 on opposite sides of the magnet-systems 7 and 7 the forces of attraction which are exerted between the ma et-systems and the plate 1 will essentially gcompensated by the forces of attraction which are exerted between the ma et-systems and the plate 12. he two groups of magnet-cores are supported by means of a bridge 15 which consists of brass or another nonmagnetizable material, the other parts of said bridge 15 being formed in the manner of circular sectors in accordance with the form; of the magnetcores of the magnet-systems 7 and 7*. The bridge 15 is provided at its peripheries with downwardly directed flanges 16, and further horizontally directed flanges 17 are provided on said flanges 16. The flanges 17 are fixed by means of screws 19 to the supporting member 18 which also carries the bearing 5 for the axle 3 of the device. At its central part the bridge 15 is provided with an aperture 20 through which the axle 3 may be passed. The upper ends of the magnet-cores may likewise be rigidl connected with each other by means of a simi ar bridge21, which, however, 18 not provided with flanges such as the flanges 16 and 17 of the bridge 15. The upper and the under parts of the magnet-cores 10 are embedded into the bridges 21 and 15 respectively, in such a manner that the ends of the magnetositioned o ositely to the plate 12 which orms the yo e or the magnet-systems 7 and 7.

In order to prevent the pole-plate 1 from exerting a one-sided magnetic pull upon the bearing 5, which would interfere with the accuracy of the work which is performed on the work-pieces, the ma arran ed exactly to eac other.

For automatically removin the workpieces after being worked upon rom the poleplate or holding plate 1 it is necessary that there is no magnetic attraction within a certain zone of the plate 1. This is accomplished according to m invention by making the ma et-systems and 7 of opposite polarity, so 53st in the plane of symmetry 14 between the two magnet-systems the magnetic action of one magnet-system will compensate the magnetic action of the other magnet-system. By means of a stripper which operates in the well-known manner, the work-pieces may now iametrical with respect et-systems 7 and 7 a are and fu y protected against an moisture as well as aga nst cooling liquid w ich may ass into the interior of the device. The pole-p ate or holding plate 1 will positively protect the inagnet-system against mtrusion of an cooly mg li uid by means of the flange 2 which extends ownwardly from the pole-plate. Practice has shown that the pole-plate'ma preferably be interrupted by ring-sha e members as above described. The con ormation of the magnet-systems is no essential feature of my invention. An essential feature of my invention, however, consists therein, that the chuck is composed of a fixed ma et-casing, a rotating pole-plate and a yoke-p ate which r0- tates together with said pole-plate. A further essential feature of my invention consists therein that the magnet-systems are acting in opposite direction and that neutral zones are provided intermediate said magnet-systems. It is obvious that my invention is not confined to electro-magnetic chucks of circular form as shown in the drawing. My invention may also be used in connection with chucks of rectangular form and having magnet-systems of a conformation which may be adapted to the rectangular form of the chuck. My invention furthermore is not confined to electro-ma netic chucks havin rotating pole-plates, as 1t may also be emp oyed in connection with chucks having a pole-plate which is slidably arranged with respect to the magnet-system.

In addition to this, my invention is not confined to the bilar arrangement of the magnet-s stem as slfhwn in the drawing, but may also employed with like success in connection with magnet-systems having any desired greater number of poles.

I claim:

1. An electro-magnetio chuck comprising two fixed magnet-systems of opposite polarity havin the form of c lindrical sectors and positione diametrically o posite to each other, the facin ends of sai magnet-systems being equally istanced from each other, an axle concentrically rotatable with respect to said magnet-systems, a pole-plate fast on said axle and positioned on one side of said ma et-systems, and a yoke plate also fast on sai axle and positioned on the other side of said magnet-systems.

2. An electro-magnetic chuck com rising a stationary magnet-system, a movab e poleplate on the one side of said magnet-s stem and a yoke-plate on the other side 0 said magnet-system, said yoke-plate being adapted to move in unison with said pole-plates 3. An electro-magnetic chuck com rising a stationary magnet-system, a po e-plate mounted above said magnet-system for rotamemes tion around a vertical axis, and a yoke-plate mounted below said magnet-system and connected with said pole-plate so as to rotate in unison therewith.

4. An electro-magnetic chuck, comprising a stationary magnet-system having the form of a cylindrical sector, an axle concentrically rotatable with respect to said magnet-system a pole-plate fast on said axle and positions on one side of said magnet-system, and a yoke-plate fast on said axle and positioned on the other side of said magnet-system.

5. An electro-magnetic chuck com rising a stationary magnet-system, a po e-plate mounted above said magnet-system so as to be rotatable around a vertical axis, and a yoke-plate mounted below said magnet-system and connected with said pole-plate so as to rotate in unison therewith, said polelatehaving a flange projecting downwardly rom its periphery and surroundingsaid magnetsystem.

6. An electro-magnetic chuck comprising two stationary ma et-systemshaving the form of c lindrica sectors and positioned diametrica 1y 0 posite to each other, the facing ends of sai magnet-systems being equally distanced from each other, an axle concentrically rotatable with respect to said magnet-systems, a pole-plate fast on said axle and positioned on one side of said magnet-systems, and a yoke-plate also fast on said axle and positioned on the other side of said magnet-systems.

7. An electro-magnetic chuck comprising a rotatable axle, a po e-plate fast on said axle, a-yoke-plate also fast on said axle at a distance from said pole-plate and a stationary magnet-system arranged intermediate said pole-plate and said yoke-plate, said magnetsystem being adapted to generate opposite polarities in diametrically opposed zones of said pole-plate.

8. An electro-magnetic chuck comprising an axle which is so mounted as to be rotatable around an essentially vertical axis, a pole-plate having annular strips of magnetlzable and non-magnetizable material and being fixedly mounted on said axle, a yokeplate of.ma etizable material, said oke- Flate being xedly mounted on said ax e beow saidpole-plate and at some distance therefrom, two groups of stationary magnetcores havin opposite polarities and bein of the shape 0 c y indrical sectors mounte intermediate sald pole-plate and said yokeplate and having their facing ends essentially at even distances from each other.

9. An electro-magnetic chuck comprisin an axle which is mounted rotatably aroun an essentially vertical axis, a pole plate having annular strips of magnetizable and nonmagnetizable material and bein fixedly mounted on said axle, a yoke-plate o magnetizable material, said yoke-plate being fixedly mounted on said axle below said pole-plate and at some distance therefrom, two groups of stationary magnet-cores having opposite golarities and being of the shape of cylinrical sectors mounted intermediate said pole-plate and said yoke-plate and having their facing ends essentially at even distances from each other, said ole-plate being provided with a downwar ly projecting flange surrounding said two grou s of fixed magnet-cores, substantially as escribed as and for the purpose set forth.

- In testimony whereof I aflix my signature.

JULIUS BING. 

